I want to create a service and make it run in the foreground.

Most example codes have notifications on it. But I don't want to show any notification. Is that possible?

Can you give me some examples? Are there any alternatives?

My app service is doing mediaplayer. How to make system not kill my service except the app kill it itself (like pausing or stopping the music by button).

As a security feature of the Android platform, you cannot, under any circumstance, have a foregrounded service without also having a notification. This is because a foregrounded service consumes a heavier amount of resources and is subject to different scheduling constraints (i.e., it doesn't get killed as quickly) than background services, and the user needs to know what's possibly eating their battery. So, don't do this.

However, it is possible to have a "fake" notification, i.e., you can make a transparent notification icon (iirc). This is extremely disingenuous to your users, and you have no reason to do it, other than killing their battery and thus creating malware.

Update: This was "fixed" on Android 7.1. https://code.google.com/p/android/issues/detail?id=213309

Since the 4.3 update, it's basically impossible to start a service with startForeground() without showing a notification.

You can, however, hide the icon using official APIs... no need for a transparent icon: (Use NotificationCompat to support older versions)

NotificationCompat.Builder builder = new NotificationCompat.Builder(context);
builder.setPriority(Notification.PRIORITY_MIN);

I've made peace with the fact the notification itself still needs to be there but for who ever who still wants to hide it, I may have found a workaround for that as well:

Start a fake service with startForeground() with the notification and everything.
Start the real service you want to run, also with startForeground() (same notification ID)
Stop the first (fake) service (you can call stopSelf() and in onDestroy call stopForeground(true)).

Voilà! No notification at all and your second service keeps running.

This no longer works in Android 7.1+. This technique may violate Google Play's developer policies (Apps that introduce or exploit security vulnerabilities.).

Instead, I suggest having the user block the service notification.

Here's my implementation of the technique in the answer by Lior Iluz.

Code

ForegroundService.java

public class ForegroundService extends Service {

    static ForegroundService instance;

    @Override
    public void onCreate() {
        super.onCreate();

        instance = this;

        if (startService(new Intent(this, ForegroundEnablingService.class)) == null)
            throw new RuntimeException("Couldn't find " + ForegroundEnablingService.class.getSimpleName());
    }

    @Override
    public void onDestroy() {
        super.onDestroy();

        instance = null;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

}

ForegroundEnablingService.java

public class ForegroundEnablingService extends Service {

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (ForegroundService.instance == null)
            throw new RuntimeException(ForegroundService.class.getSimpleName() + " not running");

        //Set both services to foreground using the same notification id, resulting in just one notification
        startForeground(ForegroundService.instance);
        startForeground(this);

        //Cancel this service's notification, resulting in zero notifications
        stopForeground(true);

        //Stop this service so we don't waste RAM.
        //Must only be called *after* doing the work or the notification won't be hidden.
        stopSelf();

        return START_NOT_STICKY;
    }

    private static final int NOTIFICATION_ID = 10;

    private static void startForeground(Service service) {
        Notification notification = new Notification.Builder(service).getNotification();
        service.startForeground(NOTIFICATION_ID, notification);
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

}

AndroidManifest.xml

<service android:name=".ForegroundEnablingService" />
<service android:name=".ForegroundService" />

Compatibility

Tested and working on:

Official Emulator
- 4.0.2
- 4.1.2
- 4.2.2
- 4.3.1
- 4.4.2
- 5.0.2
- 5.1.1
- 6.0
- 7.0
Sony Xperia M
- 4.1.2
- 4.3
Samsung Galaxy ?
- 4.4.2
- 5.X
Genymotion
- 5.0
- 6.0
CyanogenMod
- 5.1.1

No longer working as of Android 7.1.

Snicolas

You can use this (as suggested by @Kristopher Micinski):

Notification note = new Notification( 0, null, System.currentTimeMillis() );
note.flags |= Notification.FLAG_NO_CLEAR;
startForeground( 42, note );

UPDATE:

Please note that this is not allowed anymore with Android KitKat+ releases. And keep in mind that this is more or less violating the design principle in Android that makes background operations visible to users as mentioned by @Kristopher Micinski

Just set your notification's ID to zero:

// field for notification ID
private static final int NOTIF_ID = 0;

    ...
    startForeground(NOTIF_ID, mBuilder.build());
    NotificationManager mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    mNotificationManager.cancel(NOTIF_ID);
    ...

A benefit you can get is, a Service will be able to runs on high priority without destroyed by Android system, unless on high memory pressure.

EDIT

To make it work with Pre-Honeycomb and Android 4.4 and higher, make sure that you use NotificationCompat.Builder which provided by Support Library v7, instead of Notification.Builder.

I set the icon parameter to the constructor for Notification to zero, and then passed the resulting notification to startForeground(). No errors in the log and no notification shows up. I don't know, though, whether the service was successfully foregrounded--is there any way to check?

Edited: Checked with dumpsys, and indeed the service is foregrounded on my 2.3 system. Haven't checked with other OS versions yet.

There is one workaround. Try creating notification without setting icon, and the notification would not show. Don't know how it works, but it does :)

    Notification notification = new NotificationCompat.Builder(this)
            .setContentTitle("Title")
            .setTicker("Title")
            .setContentText("App running")
            //.setSmallIcon(R.drawable.picture)
            .build();
    startForeground(101,  notification);

version 4.3(18) and above hiding service notification is not possible , but you could disable the icon , version 4.3(18) and below is possible to hide the notification

Notification noti = new Notification();
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN) {
    noti.priority = Notification.PRIORITY_MIN;
}
startForeground(R.string.app_name, noti);

I've found on Android 8.0 it's still possible by not using a notification channel.

public class BootCompletedIntentReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if ("android.intent.action.BOOT_COMPLETED".equals(intent.getAction())) {

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {

                Intent notificationIntent = new Intent(context, BluetoothService.class);    
                context.startForegroundService(notificationIntent);

            } else {
                //...
            }

        }
    }
}

And in BluetoothService.class:

 @Override
    public void onCreate(){    
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {

            Intent notificationIntent = new Intent(this, BluetoothService.class);

            PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);

            Notification notification = new Notification.Builder(this)
                    .setContentTitle("Title")
                    .setContentText("App is running")
                    .setSmallIcon(R.drawable.notif)
                    .setContentIntent(pendingIntent)
                    .setTicker("Title")
                    .setPriority(Notification.PRIORITY_DEFAULT)
                    .build();

            startForeground(15, notification);

        }

    }

A persistent notification is not shown, however you will see the Android 'x apps are running in the background' notification.

You can hide notification on Android 9 by using custom layout with layout_height = "0dp"

NotificationCompat.Builder builder = new NotificationCompat.Builder(context, NotificationUtils.CHANNEL_ID);
RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.custom_notif);
builder.setContent(remoteViews);
builder.setPriority(NotificationCompat.PRIORITY_LOW);
builder.setVisibility(Notification.VISIBILITY_SECRET);

custom_notif.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="0dp">
</LinearLayout>

Tested on Pixel 1, android 9. This solution doesn't work on Android 8 or less

Block the foreground service notification

Android 7.1+ can't be exploited to hide the notification. Instead, get the user to block it.

Android 4.1 - 7.1

The only way is to block all notifications from your app:

Send user to app's details screen:

Uri uri = Uri.fromParts("package", getPackageName(), null);
Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS).setData(uri);
startActivity(intent);

Have user block app's notifications

Note this also blocks your app's toasts.

Android 8

It's not worth blocking the notification on Android O because the OS will just replace it with a "running in the background" or "using battery" notification.

Android 9

Use a Notification Channel to block just the service notification.

Assign service notification to notification channel

Send user to notification channel's settings

Intent intent = new Intent(Settings.ACTION_CHANNEL_NOTIFICATION_SETTINGS)
    .putExtra(Settings.EXTRA_APP_PACKAGE, getPackageName())
    .putExtra(Settings.EXTRA_CHANNEL_ID, myNotificationChannel.getId());
startActivity(intent);

Have user block channel's notifications

Here is a way to make your app 's oom_adj to 1 (Tested in ANDROID 6.0 SDK　emulator)．　Add a temporary service, In your main service call startForgroundService(NOTIFICATION_ID, notificion). And then start the temporary service call startForgroundService(NOTIFICATION_ID, notificion) with same notification id again, after a while in the temporary service call stopForgroundService(true) to dismiss the onging ontification.

You can also declare your application as persistent.

<application
    android:icon="@drawable/icon"
    android:label="@string/app_name"
    android:theme="@style/Theme"
    *android:persistent="true"* >
</application>

This essentially sets your app at a higher memory priority, decreasing the probability of it being killed.

redM0nk

I developed a simple media player couple of months ago. So what I believe is if you are doing something like:

Intent i = new Intent(this, someServiceclass.class);

startService(i);

Then then system shouldn't be able to kill your service.

reference: read the paragraph which discuss when system stops the service

来源：https://stackoverflow.com/questions/10962418/how-to-startforeground-without-showing-notification

标签

android

android-service

foreground

How to startForeground() without showing notification?